• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Should drainage basins be managed or natural? Discuss with use of examples from both LEDCs and MEDCs.

Extracts from this document...


Should Drainage Basins be managed or natural? Discuss with use of examples from both LEDCs and MEDCs. Drainage basins are areas in which water drains from higher land to lower land and eventually meets the sea or a lake. Water that flows on top of land along a certain path is said to be in a channel. The argument in this essay is whether drainage basins and river channels should be managed or left to flow naturally. If people try to control or alter the natural flow of water in a drainage basin in some way it is said to be managed. If a drainage basin is left alone and has not been changed or altered in any way it is said to be natural. People change drainage basins and river channels for many reasons; one of the earliest examples of drainage basin management was the irrigation of crops around the Nile in ancient Egypt. People change the landscape around them to make it easier for them to live in a particular area, this was thought of as a good thing by many when the UK was newly developing. ...read more.


The US army corps, in charge of flood prevention, had constructed lev�es, some of which were over 15 m high. They cut through meanders shortening the river (for over 1094 miles it flows in artificial channels). Large floodwater over-spills were built to take the excess water in times of flood. The Mississippi's three major tributaries (The Missuori, Ohio and Tennessee) had been controlled by dams. Despite all of all of these flood defences, the Mississippi still flooded. There were two main views on the cause of the flood; conservationists thought that the flood defences had exaggerated the flood and those in favour of the flood defences blamed it on exceptionally high rainfall. I think that the flood was caused by prolonged rainfall and that the flood defences turned what would have been a long minor flood into an extreme flash flood. This happened because the dams stored up the excess water until they were forced to release some, because of this the river level rose and caused some lev�es to be breached. Another fault of the US army corps engineers was the straightening of the river, this allowed the water to flow faster and gather more energy making it more likely to burst through the lev�es. ...read more.


When lev�es are built to "protect" crops and farmland no silt is deposited (unless lev�es are unsuccessful) and more artificial fertilisers need to be added to enrich the soil. Another reason why drainage basin management is not a good idea is the huge capital needed (although some can be retrieved through Hydroelectricity). Dams and alterations to rivers cost millions and can take years to construct. Even when they are in operation, they need constant maintenance and major repairs to dams are very difficult. It is very difficult to predict what a river is going to do and how it is going to react to changes made to it. This means that there is always a possibility that alterations made in an attempt to manage a drainage basin will not work at all or even make the problem worse. The management of drainage basins also has detrimental effects on the environment, Dams flood valleys and dry up wetland downstream e.g. in 1780 there were 41.9 million acres of wetland around the Mississippi compared to 18.1 million acres today Although I can see the need to protect settlements from flooding and the advantages of hydroelectric power, for me it is the true unpredictability and complex nature of drainage basins that makes management of them a less preferred option. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Hydrology & Fluvial Geomorphology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Hydrology & Fluvial Geomorphology essays

  1. Case Study: The Mississippi River Flood of 1993

    People and the Flood Nearly fifty people died as a result of the flooding, 26,000 were evacuated and over 56,000 homes were damaged. Economic losses that are directly attributable to the flooding totaled $10-12 billion. Indirect losses in the form of lost wages and production can not be accurately calculated.

  2. Flooding on the Mississippi

    In times of flood like the 1993 one it diverts excess water from the Mississippi along a 9km spillway, through 350 reservoirs. This spillway has dramatically reduced the flood risk at new Orleans and baton rouge. So more of these along the course of the Mississippi could be a lot of help to reduce the risk of a flood.

  1. To assess whether the modified channel of the river ash is effective in reducing ...

    We repeated the experiment on the left side and in the middle of the channel. Equipment * 30 m. measuring tape * 2 ranging poles * A cork * A stopwatch Limitations To make this experiment accurate we used the same cork in both channels.

  2. To what extent the flood alleviation scheme has had on the environment and people ...

    Swanage however is less than 20 meters above sea level. The sharp gradient on each side of Swanage means that the surface run off is on a steep slope, so precipitation makes its way very quickly towards the town centre which is a natural flood plain.

  1. Explain what it is meant by, in a drainage basin, by the terms drainage ...

    The diagram below shows the upstream and downstream effect of a dam on the cross and long profile. There has been a significant change in the alluvial morphology of the channel. Downstream degrading flattens the channel slope so much that there is insufficient energy to transport the available sediments.

  2. Describe and Explain the Factors that Influence the Flood Hydrograph, with particular reference to ...

    and after urbanisation, which will therefore help me describe the difference between rural and urban drainage basins using the factors. Figure 4 below shows a storm hydrograph with labels. Factors that influence the storm hydrograph The discharge of rivers in some drainage basins rises rapidly after a storm often leading to flooding.

  1. Investigate how the velocity of rivers changes.

    straight section of the river Rhymney will be deeper than the depth at the two banks and the velocity will be greater because at the centre of the river the only friction is from the bed of the river and on the two sides of the river the friction is

  2. How does Loughton Brook change as it moves downstream?

    We recorded the results on the recording sheets. We chose to calculate the velocity, as it is a key feature of rivers efficiency. If the velocity increases as we go downstream it again means that there will be more ware traveling through so it will again prove that the river becomes more efficient as it goes downstream.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work